How the Ancestral Puebloans in northern Arizona benefited from volcanic cinder mulch

Dan’s father, and his father’s wife, came to visit. We took them on a tour of Wupatki and Sunset Crater National Monuments, which are right next to one another northeast of Flagstaff.

We stopped at Wukoki Ruin, my favorite pueblo in Wupatki National Monument. You can see a light dusting of volcanic cinders around the ruin from Sunset Crater. The cinders used to be deeper in this area but have eroded away over the last 1000 years.

Sunset Crater, today a 1000-foot-high cinder cone, probably erupted in the 1080s. We walked up to the Bonito Lava Flow, which erupted from the base of the cinder cone. I told them to smell the ponderosa pine bark, which smells like butterscotch, and Dan’s father decided to become a tree hugger.

A thick layer of ash and cinders piled up for miles around Sunset Crater. The Ancestral Puebloans, which here included the ancestors of some Hopi clans, called the Sinagua by archeologists, noticed that native plants grew bigger and faster in areas with roughly one to four inches of cinders (deeper cinder deposits inhibit plant growth). Farmers planted in the cinder mulch. Warm season crops like corn, beans and squash benefited from the heat-retaining cinders and extra soil moisture.

The Sinagua had previously lived in small clusters of pit houses. After the eruptions began, they built pueblos from rocks and mud plaster. At its peak, the biggest pueblo in the area, Wupatki Pueblo in Wupatki National Monument, had 100 rooms and was three stories high. It housed as many as 100 or more people. The pueblo was inhabited for 150 years, until the Great Drought of the late 1200s.